ejs » programming

Weekend project – USBasp

ejs — Sun, 21 Sep 2008 18:26:50 +0000

I had some ideas to go out before, but as i got terrible cold last Friday, I had to postpone all of them.

I feel a bit better today, so decided to build USBasp – an USB port ISP programmer for Atmel product family. I used STK 200/300 dongle before, but it works from parallel port only.

Lets start: the schematics is from http://www.fischl.de/usbasp/ . You can find some schematics and pre-routed PCB’s there.

What I need is USB B type or MiniUSB connector, SMD parts, small footprint, single – sided PCB. The one I liked is by Thomas Pfeifer, http://thomaspfeifer.net/atmel_usb_programmer.htm. The problem is I found no files for Eagle there and had to re-create the PCB.

Additional features are:

RC filters on MOSI, MISO and SCK lines to suppress ringing, as suggested in AVR Freaks forum;
Signal from oscillator (XTAL1) is routed to the pin 3 on IDC connector via jumper – a handy feature to debrick the MCU if you accidentally fused external oscillator;
Inductor on the power line.

The PDF files with the layout are here, an A6 – size mirrored image for direct printing on OHP is here.

Added on 2008-10-01:

First, it works. Both connected directly or via USB hub.
Second: don’t create anything while you are ill. Actually, pin number 5 on miniUSB connector MUST be grounded, while pin number 4 can be grounded or left floating. I’ve used i jumper wire to solve the issue.

Colorization

ejs — Wed, 19 Oct 2005 18:57:50 +0000

505510

Quite interesting article on image processing. The MatLAB source, presented on the site, need some minor enhancments. Authors may contact me, if they want .
Attention: the program is really slow. I used ‘direct solver’, and it took almost 10 minutes to proceed the image.

JPEG-2000 in MatLAB

ejs — Fri, 15 Apr 2005 22:07:45 +0000

Any idea how to produce and read the JP2 file in MatLAB?
The easiest way should be writing middleware in Java to specific library. The things are complicated, as i need to get and modify data from every stage of encoding/decoding, like color space transformations, quantization, EBCOT (including bit-plane decomposition, bit-plane processing, encoding) and rate-encoders.

There is JasPer, written in C. Not all functions of Jpeg-2000 basic specification is implemented now;
Jj2000, written in Java; only basic functionality is provided;
Kakadu, written in C++ and has JNI bindings. Almost perfect inplementation of the Jpeg2000 image compression standart; data-on-demand, progressive transmision, even video encoding/decoding is supported.

As i tried to reproduce kdu_encoder in Java, no image is appearing in the output file, while original C++ file works well.

Need more timeto research.